For example, since electrical components, electric wiring and the like are set under the floor panel of aircrafts, it is necessary to shut off the moisture and humidity from the floor panel so that the moisture will not penetrate under the floor panel. However, since the floor panel is fixed onto the body frame by bolting, it is difficult to completely prevent moisture permeation from the clearance between a bolt and a screw hole formed for bolting a floor panel, even when the bolt is screwed into the screw hole. For this reason, a sealing sheet is adhered to a floor panel to shut off the floor panel from water and humidity.
In addition, an antenna to aid communication between aircrafts and distant places is set on the outer surface of the body wall (outer board) of the aircrafts. Many of such antennas have a plate-like fixing board having an electric connector protruding from one surface thereof. The surface of the fixing board having the protruding electric connector is superposed on the outer face of the outer board, the connector is inserted into the inside of an aircraft from the hole formed on the outer board of the aircraft, and connected to an appropriate electric circuit in the aircraft. In this case, the fixing board of the antenna is fixed removably with a bold on the outer board of the aircraft, where the outer board and the antenna fixing board are fixed via a gasket to block water and humidity from the outside from the fixed part. For example, US2004/0070156A1 proposes a material consisting of an adhesive sheet wherein an adhesive layer of a flexible polyurethane gel is formed on both the front and the back of a substrate film as this kind of gasket. This publication describes to maintain superior sealing property, since polyurethane gel is superior in the flexibility, elasticity, compressibility, flexibility and the like, and nonreactive with the constituent materials (specifically aluminum etc.) of the outer board of aircrafts and antenna fixing board, and water (including brine).
Aircraft members are required to have high flame retardancy. Therefore, a flame retardant is added to the aforementioned sealing sheet and gasket. Since halogen flame retardants show a high flame retardant effect, a member containing a halogen flame retardant shows high flame retardance, but the halogen flame retardant generates a large amount of toxic halogen gas by combustion. Therefore, the present inventors previously proposed a gasket composed of an adhesive sheet, which shows high flame retardance though it contains a halogen-free flame retardant (US2011/0156353 A1).